Art of converting high boiling hydrocarbon oils into lower boiling hydrocarbon oils



Febv 7, 1933. G CASH 1,896,728

ART OF CONVERTING HIGH BOILING HYDROCARBON'OILS INTO LOWER BOILING HYDROCARBON OILS Flled July 13, 1927 m a v I m a N V H. "A m Patented Feb. 7, 1933 UNITED s'rATas PATENT OFFICE GENTBY CASE, WRITING, INDIANA, ASSIGNOB '10 STANDARD OIL OOHPANY', OI

WHI'I'ING, INDIANA, A CORPORATION OF INDIANA AB'I' OI CONVERTING HIGH BOILING HYDROGABBON OILS INTO LOWER BOIIING HYDROCABBON OILS Application fled July 18,

' thereof, illustrated by the accompanying drawing, wherein apparatus suitable for carrying the invention 1nto effect is illustrated diagrammatically in section.

Referring more particularly to the drawing, the numeral 5 lndicates diagrammatically a furnace setting, wherein is mounted a continuous coil 6, heated b any suitable heatin means, for example, t 0 burner 7. This 0011 is diagrammatically illustrated it is to be noted in connection therewith, however, that the ortion last traversed by the 011 is, in the orm shown, that directly ex sed to the radiant heat of the flame and is indicated by the numeral 6. From the outlet' of the coil 6, a line 7 leads to the two enlarged chambers 8, being provided with the valved connections 9 leading into the latter. The enlarged chambers 8 are provided with means for preventing 28 any substantial drop 'in temperature belowthe outlet tem erature of the oil leaving the coil 6. In the orm illustrated, this is effected by providing around the chambers 8 a setting 10, in which a heated gaseous atmosphere to is maintained by means of the small burners 11. By this means the chambers 8 are surrounded by an insulating blanket of hot gases which may be as hot as or slightly hotter than the oil contained therein. It is readily underuistood that other means for preventing substantial temperature drops may be employed, for example, a suitable insulating lagging surrounding the chambers.

The chambers 8 are illustrated as comparae0 tively elongated vertical cylinders. From the u r rtion thereof. vapor lines 12 are proviigd liich lead to the manifold '13. The latter, is connected by the pipe 14 with the lower portion of a dephlegmating tower 15,

within which'fractionating plates 16 of any suitable type are rovided. In the upper portion 'of the deph egmating to'wer- 15 suitable cooling means, suchas the coil 17 are provided. Uncondensed vapors pass'out of the dephlegmating tower 13 through the vapor oiling hydro-- 1027. Serial no. 205,810.

line 18 which leads to any suitable condensing and pressure maintaining devices.

Means, such as the valved discharge pipes 19, are provided for the withdrawal of tar or unvaporized liquid products from the lower portions of the chambers 8.

Liquids condensed in the de hlegmating tower 15 are withdrawn throug pipe 20 by pump 21. and forced through the pipe 22 into the later portion of the coil 6, and in the form illustrated, in that portion 6 which is directly exposed to the radiant heat of the flame. A stream of oil to be converted is fed to the coil 6 through the line 23 by any suitable means. In operation, the oil to be converted, which is pre erably a distillate stock of the character of gas oil and may contain products which have 1previously been sub'ected to pressure crac ing conditions, is oroed by 70 any suitable means through the line 23 into I and through the coil 6. In the 'coil 6, the oil is brought to conversion temperatures above 700 F. and preferably to 800 F. or higher. At a point in the coil at which the oil stream flowing therethrough has attained a cracking temperature, and preferably-in the later portion of the coil exposed to radiant heat of the flame, the cooler reflux condensate formed in the dephlegmating tower .15 is forced into so the stream of oil and carried with it. In I normal operation upon a stock of approximately gas oil gravity, the proportion of liquid thus su plied may be 1 to 1.5 times the volume (cold of the oil fed into the coil through the line 23. The mixed oils at conversion temperature are discharged through the line 7 into the stills 8,. through which they may flow in series or in parallel. In the form illustrated, parallel flow into the stills is employed. In the stills 8 conversion temperatures equal to or somewhat below the temperature of the oil at the outlet from the coil 6 are maintained. For example, the temperature at the outlet of the coil may be 830 95 to 850 F. and that maintained within the chambers 8 from 750 to 800 F. 'A pressure in excess of 4 atmospheres, and preferably of 20 atmos heres or higher is maintained within the c ambers 8.

The vapors evolved from the oil and separated in the chambers '8 are discharged throu h the pipes 12 into a manifold 13 and pass tlirough line 14 into the dephlegmating column 16, in which the va ors of conversion products of higher boiling point range than the desired gasoline-like products are condensed by the passage of a suitable cooling medium, such as oil to be subjected to the conversion process, through the coil 17. The reflux condensate, which is highly heated, say at 650 to 680 F., is withdrawn through the line 20 and forced by the hot oil pump 21 through the line 22 and to the later portion of the coil 6, as hereinbefore described.

In operations as hitherto conducted, it has been customary to introduce the reflux condensate into the stream of fresh oil passing through the furnace in which the latter is brought to conversion temperature at approximately the beginning of the coil or at some comparatively early intermediate point before the oil has attained a conversion temperature. By carryin out the operation as hereinbefore describe introducing the refluxinto the later portion of the coil at a point at which the oil stream has attained a conversion temperature, it has been found that the capacity of a given unit or piece of apparatus may be very substantially increased, in some cases, practically doubled,

without decreasing efficiency or substantially affecting the rate of conversion in the unit. Furthermore, the introduction of the reflux condensate in the manner described so greatly increases the rate of flow and the heat transfer in the later portion of the coil that it is possible and effective to subject the mixed stream of oil thereafter to the full radiant heat of the flames, suitably simultaneously with the heat of the combustion ases.

Although the present invention has been described in connection with the specific de tails of a procedure for carrying it into effect, it is not intended that these details shall be regarded as limitations upon the scope of the invention, except in so far as included within the accompanying claim.

I claim:

The method of effecting conversion of hydrocarbon oils into lower boiling hydrocarbon oils such as gasoline, which comprises passing the hydrocarbon oils to be converted in a continuous 'stream through a heating zone in which they are brought to conversion temperature and are subsequently passed through a portion of the heatin zone in which they are subjected to the direct radiant heat of the flame, separating from the heated oil products leaving the heating zone vapors of converted products including the desired low boiling products, cooling the separated vapors to condense and remove therefrom products heavier than gasoline as 

